Field of the Invention
The invention relates to a rotor for a turbogenerator.
In a generally known rotor such as this, insulation is used to ensure that the necessary creepage distances are complied with in the gas outlet zone. The thickness of the insulation between the damper winding and the field winding depends on the physical configuration of the winding bars, and on the required creepage distances in the gas outlet zone.
The insulation is generally formed with a constant wall thickness over the entire slot length.
If a specific slot depth is specified, as is the case in particular with replacement windings for rotors which are already in use, then the insulation between the damping winding and the field winding can lead to a reduction in the space available for the field winding in order to maintain a height which is resistant to creepage currents, as a result of which both the copper cross section and any gas channel which may be present are constrained for each conductor. If the rated field current is maintained or is increased, then considerably more winding heating occurs, while the gas flow rate is reduced at the same time.
This results in the object of specifying a rotor of the type mentioned initially in which the distance between the field winding and the damper winding is minimal, despite complying with the required creepage distances.
According to the invention, this object is achieved by a rotor for a turbogenerator having a field winding which is formed from hollow conductors, having a damper bar, having insulation arranged between the damper bar and the field winding, having a wedge and having a gas outlet zone which is located in the central rotor region, in that the damper bar is interrupted and is replaced in the region of the gas outlet zone by an insulating piece, and in that the parts of the damper bar are electrically conductively bridged by the wedge.
It is thus possible to achieve the desired number of conductors, each having the same overall cross-sectional area (copper cross section and gas channel cross section) for a specified slot depth, irrespective of whether this relates to a replacement winding or a new winding. The novel solution makes it possible to advantageously use continuous copper hollow conductors to replace field winding bars which are designed with hollow conductors and with interrupted flat copper in the region of the gas outlets, with the original wedge and damper bar height (with insulation) being maintained, so that the same rotor slot cross-sectional area and the same external contour are available for accommodation of the field winding as for the original winding.
Furthermore, the original wedges and the original damper conductors can still be used, after minor modifications.
According to one preferred refinement, a bridge wedge which is composed of electrically highly conductive material engages over an insulating piece which is fitted in the region of the gas outlet in order to form a creepage distance, as well as in each case one subregion of the adjacent damper bar parts on both sides of the insulating piece. The remaining wedge pieces, which engage over the damper bar parts in those regions where there is no gas outlet, may be composed of electrically less highly conductive material. In order to improve the electrical contact, an electrically conductive wedge attachment is arranged between the wedge and the damper bar parts, as well as the insulating piece. Securing elements are provided between the wedge and damper bar parts, in order to prevent relative movement.
The rotor according to the invention will be described with reference to an exemplary embodiment and the schematic FIGS. 1 and 2.